NEC PD78078 用户手册
271
CHAPTER 11 WATCH TIMER
11.3 Watch Timer Control Registers
The following two types of registers are used to control the watch timer.
• Timer clock select register 2 (TCL2)
• Watch timer mode control register (TMC2)
(1) Timer clock select register 2 (TCL2)
This register sets the watch timer count clock.
TCL2 is set with an 8-bit memory manipulation instruction.
RESET input sets TCL2 to 00H.
Remark
Besides setting the watch timer count clock, TCL2 sets the watchdog timer count clock and buzzer
output frequency.
Figure 11-1. Watch Timer Block Diagram
Selector
TMC21
Prescaler
Selector
Selector
Selector
INTWT
5-Bit Counter
f
W
2
14
f
W
2
13
INTTM3
To 16-Bit
Timer/Event
Counter
Timer/Event
Counter
Watch Timer Mode Control Register
TMC26 TMC25 TMC24 TMC23 TMC22 TMC21 TMC20
Internal Bus
TCL24
Timer Clock Select Register 2
f
W
2
4
f
W
2
5
f
W
2
6
f
W
2
7
f
W
2
8
f
W
2
9
f
W
f
XX
/2
7
f
XT
Clear
Clear
3